Fuel distributing valve



Jan. 2, 1951 L. s. GREENLAND FUEL DISTRIBUTING VALVE 2 Sheets-Sheet 1Filed April 16, 1946 J Wm,

Jan. 2, 1951 s. GREENLAND FUEL DISTRIBUTING VALVE 2 Sheets-Sheet 2 FiledApril 16, 1946 UWUIO Patented Jan. 2, 1951 England, assignor to H. M

. Hobson Limited,

London, England, a company of Great Britain Application Apr-i116, 1946,(serial No. 362,487 Ira-Great Britain May 22, 1945 4 Claims. 1

This invention relates to fuel injection systems for internal combustionengines of the type in which fuel is injected into the engine from adistributor through pipes leadin each "to "one of a plurality of nozzlessituated around the periphery of the engine at different levels. Sucharrangements are used with combustion turbine engines, and the nozzles:are often arranged in a circle of considerable diameter so that thereare substantial differences in the hydraulic head in the severaldistributing pipes. The effects of these differences are .not materialwhen the englue is running under conditions such that there is a highpressure in the inlet line by which fuel is fed to the distributor.When, however, the fuel pressure in the inlet line falls to low values,the diifer'ences in hydraulic head may lead to serious unevenness ofdistribution of fuel to the nozzles.

The invention provides a fuel distributor for use in an injection systemof the above character, comprising a cylinder having an inlet forconnection to the fuel inlet line, a .piston valve located in thecylinder, a plurality of radial holes in the cylinder eachcommunicating, via a restricted passage, with an outlet for connectionto a "delivery pipe leading to one of the nozzles, and a springoperating on "the valve in opposition to the fuel pressure at the inlet,which spring is normally overpowered by the fuel pressure so that theholes are unobstructed by the valve, but is effective to cause partialobstruc tion of the holes when the fuel pressure at the inlet fallsbelow a given value, the disposition of the holes and/or the shape ofthe valve head being such that, under these conditions, the effectiveareas of the holes are such as to counteract the differences inhydraulic head in the associated delivery pipes and tend to equalise therate of flow of fuel through the nozzles.

To achieve this result, the effective area of a hole leading to adelivery pipe in which there is a large hydraulic head must be greaterthan that of a hole leading to a pipe in which there is a smallerhydraulic head; and a considerable degree of equalisation of the fuelflow through the nozzles can be achieved by suitable selection of thelocation of the holes and/or of the shape of the valve head.

The required 'equa'li'satlon can be effected by employing a level valvehead, i. e. a valve head extending in a plane at right angles to theaxis of the cylinder, and arrangin the holes at different levels in thecylinder, so that they will be progressively obstructed by the valvehead 2 in the proper sequence as the "valve is moved towards the holesby its spring.

It is however more convenient from a manufacturing standpoint to locatethe holes at the same level in the cylinder and to arrange "fordifferential masking thereof by the valve by appropriate shaping of "thevalve head. The valve head can be given an oblique continuous edge, sothat as it moves into cooperation with the holes these will be blankedoff to the extent necessary to counteract the effect of the varyinghydraulic heads in the delivery pipes. This arrangement, however,necessitates very accurate location of the valve in the radialdirection, and I prefer to form the valve head with stepped lands, 1. e.lands of different height, each land cooperating with one of the holes.Preferably also the lands are separated by axially extending slots inthe valve head, so as to permit of individual grinding of the lands,

The dimensions of the spring against the piston valve-are "such that theaction of unmaskin the holes in the "cylinder is completed when the fuelinlet pressure is 'suflicient to reduce the unevenness of distributionto acceptable limits. Above this pressure, the valve is "restrained fromfurther movement and the how of fuel to each nozzle is then determinedby the calibrated restrictions. 7

One specific embodiment of the invention, as applied to a fueldistributor for use in a fuel supply system for a combustion turbineengine of the kind described in my copending application Serial No.669,653, filed May 14, 1946, will now be "described in further detail,by way of example, with reference to the accompanying drawings in which:

Fig. 1 is a diagram showing the fuel distributor and the pipes leadingto the different nozzles,

Fig. '2 is a vertical section through the fuel distributor, and Fig. 3is an enlarged development view of the valve head.

Considering first of all Fig. 1, the distributor 'IU has to distributefuel from an inlet pipe '45, via eleven distributing pipes 3I4I toeleven injection nozzles I "2| arranged in a circle in 'a verticalplane, the diameter of which circle maybe of the order of three feet.Consequently, when the fuel pressure in the inlet pipe is low, therewill be substantial differences in hydraulic head in the distributing,pipes, the head in the pipes '40, 4|, 3|, 32 leading to the uppernozzles being much greater than that in those 35-48 leading to the lowernozzles. The distributor l0 serves to equalise these differences inhydraulic 3 head at low fuel inlet pressures as will now be describedwith reference to Figs. 2 and 3.

The distributor l0, which is mounted on a supporting panel 25, comprisesupper and lower body portions '22, 23 secured together by bolts 24, anda top cover plate 26 and a bottom cover plate 21 respectively held inposition by bolts 28, 29. Within the upper body'portion 22 is a cylinder30, in which is slidably mounted a piston valve 42. A set screw 43,engaging in slot 44 in the valve 7 "42, prevents the latter from turningin the cylinder 30.

The lower end of the cylinder communicates with an inlet 45, to which isconnected the fuel inlet pipe 45. Above the inlet 45 is a filter 41,located in position by a spring 48. Access of fuel from the inlet 45 tothe lower end of the cylinder 30 is controlled by a mushroom valve 49,having a spring for pressing it against a seating 51. When the engine isstopped, the valve 49 is closed and cuts oil the cylinder 39 from theinlet 45, fuel for starting the engine being delivered from the inlet 45through a starting line 52 connected to an outlet 53 located below thevalve 49. For starting purposes fuel is fed to line 46, in accordancewith known practice, from a priming pump (not shown) and is thence fedto the engine through the starting line 52 which is, at other times,closed by the usual priming cock (not shown).

When, however, the engine is running, valve 49 is held open by the fuelpressure at the inlet, and the fuel is able to flow into the cylinder30. In the cylinder are provided eleven radial holes 54 located at thesame level, i. e. in a common plane normal to the axis of the cylinder.Each hole communicates with an outlet 55 through a radial passage 55containing a calibrated restriction 51. To these outlets are connectedthe distributing pipes which lead to the nozzles, one of these pipesbeing shown at 33 in Fig. 2.

The valve 42 is balanced against the fuel inlet pressure by a spring 53,the compression of which can be adjusted by a screw 59. Under normalconditions the fuel pressure holds the valve 42 U above the level of theholes 54, so that the valve offers no restriction to flow through theholes, the flow to the nozzles being determined solely by therestrictions 5'1. Under these conditions the differences in hydraulichead in the distributy ing pipes are unimportant.

When, however, the fuel inlet pressure falls below a given value, thevalve 42 moves down into the position shown in Fig. 2, in which its headpartially obstructs the holes 54. The valve head, as shown in Fig. 3, isformed with eleven stepped lands 6l1l, separated by axial slots 66. Eachland cooperates with one of the holes 54, and the height of the lands issuch that the differential masking of the holes 54, when the valve isoperative, tends to equalise the differences in hydraulic head, theeffective areas ofthe holes.

leading to the top nozzles being larger than the efiective areas of theholes leading to the bottom leakage then being very small and notdisturbing the equalisation of pressure between the nozzles. At normalpressures, the upper end of the valve 42 is held by the fuel pressure insealing engagement with a surface 14 and the passage 12 is closed. Theamount of leakage past the valve 42 is determined by the pressure dropacross the hole 54 and restriction 51. The restriction 5'1 is designedto take account of this leakage during calibration of the apparatus.

What I claim as my invention and desire to secure by Letters Patent is:

1. A fuel distributor, for use in distributing fuel to a plurality oflocations at different levels in relation to the distributor, saiddistributor comprising a cylinder having an inlet for admitting fuel tothe cylinder, a piston 'valve mounted to slide in and constrainedagainst rotation in relation to the cylinder and having a head exposedto the fuel pressure at the inlet, a plurality of holes in the cylindereach communicating, via a restricted passage, with an outlet for feedingfuel to one of said locations, and a spring operating on the valve inopposition to the fuel pressure at the inlet, said spring being normallyoverpowered by the fuel pressure, so that all of the holes areunobstructed by the valve but being effective to move the valve to anoperative position, in which its head partially obstructs the holes,when the fuel pressure at the inlet falls below a given value and thevalve head and holes then cooperating to effect differential reductionof the eifective areas of the holes for the purpose of counteractingdifferences of hydraulic head at the outlets.

2. A fuel distributor as claimed in claim 1, in which the holes arelocated at the same level in the cylinder and the valve head is shapedto provide differential masking of said holes when the valve is inoperative position.

3. A fuel distributor as claimed in claim 1, in which the holes arelocated at the same level in the cylinder and the valve head is formedwith stepped lands, each land cooperating with one of the holes, whenthe valve is in operative position, the lands effecting differentialmasking of the holes so as to counteract variations in hydraulic head atthe outlets.

4. A fuel distributor as claimed in claim 1, in which the holes arelocated at the same level in the cylinder and the Valve head is formedwith stepped land s, said lands being separated by axially extendingslots, each land cooperating with one of the holes when the valve is inoperative position, the lands effecting differential masking of theholes so as to counteract variations in hydraulic head at the outlets.

LEONARD SIDNEY GREENLAND.

REFERENCES CITED The following references are of record in the file ofthis patent: V

UNITED STATES PATENTS 'France July 23, 1934

